Fastening for small engine carburetor air cleaner

ABSTRACT

A carburetor air cleaner comprising a filter element confined between top and bottom shell members has a tube secured to its top wall and extending down through the filter element. The carburetor air duct has an extension projecting up into the tube through a hole in the bottom shell wall. A spring ring surrounds the extension, axially confined by a circumferential ledge on its upper end. The ring has integral fingers that press the bottom shell wall down against another circumferential ledge on the duct, and has other, curved, fingers that snap over an inturned circumferential flange on the bottom of the tube.

United States Patent 1 Gumtow 1 Mar. 12, 1974 [54] FASTENING FOR SMALLENGINE 3,167,416 1/1965 Humbert,Jr. 155/510 X CARBURETOR AIR CL3,218,785 11/1965 Tietz 55/503 [75] Inventor: g/erbert A. Gumtow,Brookfield, Primary Examiner prank w. Lutter Assistant Examiner-WilliamCuchlinski, Jr.

[73] Assignee: Briggs & Stratton Corporation, 4

Wauwatosa, Wis. [57] ABSTRACT [22] Filed; J l 21, 1972 A carburetor aircleaner comprising a filter element Appl. No.: 274,085

US. Cl. 55/502, 24/213 B, 55/503,

confined between top and bottom shell members has a tube secured to itstop wall and extending down through the filter element. The carburetorair duct has an extension projecting up into the tube through a hole inthe bottom shell wall. A spring ring surrounds the extension, axiallyconfined by a circumferential ledge on its upper end. The ring hasintegral fingers that press the bottom shell wall down against anothercircumferential ledge on the duct, and has other, curved, fingers thatsnap over an inturned circumferential flange on the bottom of the tube.

5 Claims, 2 Drawing Figures FASTENING FOR SMALL ENGINE CARBURETOR AIRCLEANER This invention relates to carburetor air cleaners for smallinternal combustion engines, and the invention is more particularlyconcerned with means for securing such an air cleaner to a carburetorair duct on which the air cleaner is installed, and for holding thecomponents of the air cleaner readily separably assembled with oneanother.

On small gasoline engines it is usual to fasten an air cleaner acrossthe air duct of the carburetor for the engine, to filter'the combustionair drawn into the carburetor mixing chamber. An air cleaner of thegeneral type of which this invention relates is disclosed in US. Pat.No. 2,999,562, to L. J. Lechtenberg. In general, it comprisescomplementary. top and bottom metal shell members which enclose a filterelement of polyurethane sponge or similar porous material and a rigidtubular member that extends through the filter element and has its endsin contact with the top and bottom walls of the shell to support andreinforce them. Air is drawn into the air cleaner shell through holes inits bottom wall, then passes through the filter element, which has itsupper surface spaced from the top wall of the shell. The tubular memberhas circumferentially spaced apart cutouts or slots in its upperportion, above the level of the top surface of the filter elements andthrough these the filtered air flows into the interior of the tubularmember and thence axially into the carburetor air duct.

The air cleaner of the Lechtenberg patent is secured in place by anelongated stud that is coaxial with the carburetor air passage and withthe tubular member. At its lower end this stud is threaded into aspider-like support in the carburetor air passage. The upper end portionof the stud projects through the top wall of the top shell member andreceives a nut which secures the air cleaner to the carburetor air ductand also holds the air 4 well as of the inlet portion of the carburetorbody casting. Furthermore, if the stud became bent as was easilypossible it could interfere with properoperation of the choke. However,the use of such a stud fastening has long been conventional incarburetor air cleaners for gasoline engines, and while itsdisadvantages were too obvious to be overlooked, they were apparentlyaccepted as inevitable.

The other disadvantage of the air cleaner of the Lechtenberg patent wasthat it required a resilient grommet or sealing member of special andrather complicated shape that extended through a hole in the bottom wallof the bottom shell member and up into the rigid tubular member, andwhich embraced the outer end portion of the carburetor air duct. Thisgrommet, which provided a sealing connection between the carburetor airduct and the air cleaner, was a relatively expensive molding.

By contrast with the prior constructions, the present invention has forits object to provide a means for securing an air cleaner to thecarburetor body of a small gasoline engine without the need for theheretofore conventional stud, and in such a manner that it is possi bleto obtain a good seal between the air cleaner and the carburetor bodywith a simple flat annular gasket.

Consistently with its objective of materially simplifying theconstruction of the carburetor body of a small engine, the air cleaner,and the means connecting the same, the present invention has for anotherof its objects the attainment of a substantial reduction in the cost ofthese components, and thus of small engines generally. The inventionachieves this objective to the extent of effecting a cost saving on theorder of three to five cents per engine. I

It is also an object of this invention to provide an air cleaner forsmall engines that can be disassembled and reassembled without the useof tools, to thereby facilitate the cleaning of its filter element.

With these observations and objectives in mind, the manner in which theinvention achieves its purpose will be appreciated from the followingdescription and the accompanying drawings, which exemplify theinvention, it being understood that such changes in the specificapparatus disclosed herein may be made as come within the scope of theappended claims.

The accompanying drawings illustrate one complete example of anembodiment of the invention constructed according to the best mode sofar devised for the practical application of the principles thereof, andin which:

FIG. 1 is a disassembled perspective view of an air cleaner of thisinvention, shown in relation to a portion of a carburetor on which it isto be installed, portions being shown broken away; and

FIG. 2 is a vertical sectional view of the air cleaner and a portion ofthe body of a carburetor to which it is attached, the view being takenon two vertical planes which are substantially normal to one another andintersect on the axis of the air duct.

Referring now more particularly to the accompanying drawings, thenumberal 5 designates the inlet end portion of a combustion air duct ofa gasoline engine carburetor, upon which is installed an air cleaner 6embodying the principles of this invention. The air duct will berecognized as part of a carburetor body that is ordinarily formed as adie casting, and its inlet portion leads to-a conventional chokebutterfly 7. In this instance the air duct is illustrated and describedas having its inlet portion opening upwardly, but it will be understoodthat this is merely by way of example and that the orientation of thecarburetor air inlet is not material to the present invention.

In general theair cleaner 6 comprises complementary top and bottom shellmembers 9 and'10 and a filter element 11 of foam polyurethane or similarresilient, spongy material.

Each of the shell members is a unitary stamping having the shape of ashallow pan. Thus the bottomshell member 10 has a flat bottom wall 12and has a low upright side wall 13 extending all around it thatterminates at its upper edge in an outwardly flared rim 14. The topshell member 9 has a generally flat top wall 15 and has a downwardlyprojecting side wall 16 extending all around it that terminates in astepped rim with an outwardly projecting ledge or shoulder 17 and adownwardly projecting lip 18.

When the shell members are assembled with the filter element 11 confinedbetween them, an integral laterally projecting ridge 20 on the filterelement, about midway between its top and bottom surfaces and extendingall around it, is confined under compression between the outwardlyflared rim 14 on the bottom shell member and its opposing ledge orshoulder 17 on the top shell member. The compressed ridge 20 on thefilter element serves as a seal between the shell members, and its outeredge is protected by the lip 18 on the top shell member.

The top shell member can be imperforate. The bottom wall 12 ofthe-bottom shell member has one rather large hole 22 that provides forconnection and communication with the carburetor air inlet, as describedhereinafter, and has a plurality of smaller holes 23 through which aircan enter the filter element.

A rigid tubular member 24, somewhat larger in diameter than thecarburetor air duct, extends between the top wall of the top shellmember and the bottom wall 12 of the bottom shell member, through aclosely fitting hole 25 in the filter element. The upper portion of thetubular member is axially notched'to define a plurality ofcircumferentially spaced fingers 26, the tip portions of which areturned radially outwardly to provide lugs 27 which are flatwise securedto the underside of the top wall 15 of the top shell member, as by spotwelding. The notches or spaces 28 between the fingers 26 permit air topass between them in flowing into the interior of the tubular member andthence into the carburetor air duct. It will be observed that the heightof the filter element is such that its top surface is spaced below thetop shell wall 15 to permit filtered air to flow across it and into thetubular member. Flange-like radially outward projections 29 at thebottoms of the notches or cutouts 28 in the tubular member overlie theupper surface of the filter element around the hole 25 therein andcooperate with the ridge thereon in confining the filter element againstupward displacement in the air cleaner shell.

At its bottom the tubular member 24 has a radially inturnedcircumferential flange 30 that overlies the bottom wall 12 of the shell;Around the hole in the filter element, at the bottom thereof, the filterelement has a radially inwardly projecting circumferential ridge 32which is compressively confined between the flange on the tubular memberand the bottom wall 12 of the shell, to provide a seal between them.

According to the present invention, the carburetor air duct has acircumferential radially outwardly projecting flange 33 which ispreferably formed integrally with the carburetor body and upon which thebottom shell member 10 rests. More specifically the flange 33 isoverlain by that portion of the bottom wall 12 which is marginal to thelarge hole 22 therein. A flat annular gasket 34 is confined between theflange 33 and the shell wall 12 to provide a seal between them.

On the carburetor air duct there is a collar-like extension 35 which ispreferably formed integrally with the duct and which projects axiallybeyond the flange 33 and into the tubular member 24. Embracing thisexten-' sion in an axially deep spring ring 36 that secures the aircleaner to the air duct and also serves to hold the air cleanerassembled. The spring ring is confined against axial outwarddisplacement relative to the extension 35 by a circumferential shoulderon the outer end of the extension, defined by an integral ledge-likeradially outward projection 40 thereon. The spring ring can neverthelessbe installed and removed over the ledge 40 by reason of the fact thatthe spring ring has an axially extending slit 37 all the way along oneside of it so that it can be radially expanded.

Formed integrally with the spring ring are two sets of spring fingers,respectively designated 38 and 39, all of which project obliquelyaxially toward the flange 33 and radially outwardly. The fingers of eachset are circumferentially spaced from one another.

The fingers 38 are generally straight and have their tips engaged withthe upper surface of the bottom wall 12 of the shell, adjacent to thehole 22 therein, to press that shell wall down toward the flange,compressing the gasket 34 and securing the bottom shell member to theair duct 5.

Each of the flanges 39 is curved along its length, as at 41, to have aconvex radially outer surface. The fingers 39 engage over the inturnedflange 30 on the bottom of the tubular member 24, and since'that memberispermanently secured to the top shell member, the fingers 39 thus serveto hold the components of the air cleaner assembled with one another.

The bottom shell member is placed on the flange 33 or, more accurately,over the gasket 34 which over- I lies that flange before the spring ringis assembled with the air duct extension 35. When the spring ring is putin place, downward pressure may have to be exerted on the bottom shellmember to compress the gasket slightly, since the straight springfingers 38 very snugly engage the bottom wall 12 of the shell, holdingit very tightly. Normally there is no occassion to remove the bottomshell member from the air duct, but if it should have to be taken off,it can be released by radially expanding the spring ring and drawing itup over the ledge 40 on the air duct extension.

With the filter element in place in the bottom shell member, and withthe tubular member permanently secured to the top shell member, the topshell member can be readily installed merely by pushing it down untilthe curved spring fingers 39 snap overthe inturned flange 30 on thebottom of the tubular member. The air cleaner can be disassembled justas readily, by forcing the top shell member upward to cause the springfingers 39 to be cammingly retracted by the flange 30 until that flangecan pass them.

To prevent the flange 30 from compressing the spring fingers 38 and thusfreeing the bottom shell member as the top one is being installed, thereare notches or cutouts 43 in the inturned flange 30, of such size and solocated as to just clear the spring fingers 38.

From the foregoing description taken with the accompanying drawings itwill be apparent that this invention provides very simple andinexpensive means for securing an air cleaner to the air duct of acarburetor and for holding the air cleaner assembled in a manner whichpermits it to be readily disassembled for servicing of its filterelement.

Those skilled in the art will appreciate that the invention can beembodied in forms other than as herein disclosed for purposes ofillustration.

The invention is defined by the following claims:

1. The combination of an internal combustion engine carburetor having acombustion air duct, and an air cleaner which is secured over an inletend of said duct and which comprises top and bottom complementary shellmembers enclosing a filter element and a substantially rigid tubularmember which extends between the shell member and through the filterelement concentrically to the duct, characterized by:

A. an integral flange on the exterior of said duct that is spaced fromsaid end thereof and defines a circumferential surface axially facingsaid end of the duct, which surface is sealingly overlain by a marginaledge portion of a wall of the bottom shell member;

B. a ring embracing said duct axially outwardly of said flange andhaving a plurality of integral circumferentially spaced resilientfingers that project obliquely radially outwardly and axially towardsaid flange;

1. certain of said fingers having their free ends engaged with saidmarginal edge portion of the bottom shell member to sealingly confine itagainst the flange, and v 2. others of said fingers being curved alongtheir lengths to have convex radially outer surface portions;

C. cooperating means on said ring and on the exterior of the duct forconfining the ring against axially outward displacement relative to theduct;

D. said tubular member having circumferential edge portions whichcompress said other fingers radially inwardly as the tubular member ismoved axially toward the flange and over which said other fingers engagewhen the tubular member is seated on said marginal edge portion of thebottom shell member, to releasably confine the tubular member againstdisplacement; and

E. said tubular member being secured to the top shell member so that thelatter is held in place in consequence of confinement of the tubularmember by said other fingers.

2. The combination of claim 1, wherein the ring has an axial slit alongthe full length thereof and wherein said member for releasably confiningthe ring against axially outward displacement relative to the ductcomprises:

radially outwardly projecting ledge means on said end of the duct whichengages the axially outer edge of said ring.

3. The combination of claim I, further characterized by:

a flat annular gasket confined between said flange and said marginaledge portion of said wall of the bottom shell member.

4. The combination of claim 1, further characterized saidcircumferential edge portions (in the tubular member being defined by aradially inwardly projecting circumferential flange thereon whichfiatwise overlies said marginal edge portion of said wall of the bottomshell member.

5. In an internal combustion engine having a carburetor with an air ductand having an air cleaner secured across an inlet end of said duct andcomprising complementary top and bottom shell members, a filter elementenclosed by said shell members, and a rigid tubular member which extendsbetween walls of the shell members through the filter element and whichis coaxial with the air duct, means for securing the air cleaner to theair duct and for holding the components of the air cleaner releasablyassembled with one another, the last mentioned means comprising:

A. means on the air duct defining l. a circumferential radiallyoutwardly projecting flange,

2. an extension of the duct which projects axially beyond the flange andinto the air cleaner through a hole in a wall of the bottom shellmember, and

3. radially outwardly projecting ledge means on the outer end of saidextension, spaced from the flange;

B. an axially slitted spring ring embracing said extension and confinedagainst axial displacement by said ledge means, said spring ring havinga plurality of circumferentially spaced integral fingers that projectobliquely toward said flange and radially outwardly,

. certain of said fingers having their free ends engaged with said wallof the bottom shell member adjacent to the hole therein, to confine thesame against the flange, and

2. others of said fingers being curved along their lengths to haveconvex radially outer surfaces; and

C. the tubular member 1. having a radially inwardly projectingcircumferential flange which overlies said wall of the bottom shellmember around said hole therein and over which said other fingers engageto releasably confine the tubular member against axial displacement, and

2. being secured to the top shell member so that the latter is held inplace by the engagement of said other fingers with the tubular member.

1. The combination of an internal combustion engine carburetor having acombustion air duct, and an air cleaner which is secured over an inletend of said duct and which comprises top and bottom complementary shellmembers enclosing a filter element and a substantially rigid tubularmember which extends between the shell member and through the filterelement concentrically to the duct, characterized by: A. an integralflange on the exterior of said duct that is spaced from said end thereofand defines a circumferential surface axially facing said end of theduct, which surface is sealingly overlain by a marginal edge portion ofa wall of the bottom shell member; B. a ring embracing said duct axiallyoutwardly of said flange and having a plurality of integralcircumferentially spaced resilient fingers that project obliquelyradially outwardly and axially toward said flange;
 1. certain of saidfingers having their free ends engaged with said marginal edge portionof the bottom shell member to sealingly confine it against the flange,and
 2. others of said fingers being curved along their lengths to haveconvex radially outer surface portions; C. cooperating means on saidring and on the exterior of the duct for confining the ring againstaxially outward displacement relative to the duct; D. said tubularmember having circumferential edge portions which compress said otherfingers radially inwardly as the tubular member is moved axially towardthe flange and over which said other fingers engage when the tubularmember is seated on said marginal edge portion of the bottom shellmember, to releasably confine the tubular member against displacement;and E. said tubular member being secured to the top shell member so thatthe latter is held in place in consequence of confinement of the tubularmember by said other fingers.
 2. being secured to the top shell memberso that the latter is held in place by the engagement of said otherfingers with the tubular member.
 2. others of said fingers being curvedalong their lengths to have convex radially outer surface portions; C.cooperating means on said ring and on the exterior of the duct forconfining the ring against axially outward displacement relative to theduct; D. said tubular member having circumferential edge portions whichcompress said other fingers radially inwardly as the tubular member ismoved axially toward the flange and over which said other fingers engagewhen the tubular member is seated on said marginal edge portion of thebottom shell member, to releasably confine the tubular member againstdisplacement; and E. said tubular member being secured to the top shellmember so that the latter is held in place in consequence of confinementof the tubular member by said other fingers.
 2. The combination of claim1, wherein the ring has an axial slit along the full length thereof andwherein said member for releasably confining the ring against axiallyoutward displacement relative to the duct comprises: radially outwardlyprojecting ledge means on said end of the duct which engages the axiallyouter edge of said ring.
 2. an extension of the duct which projectsaxially beyond the flange and into the air cleaner through a hole in awall of the bottom shell member, and
 2. others of said fingers beingcurved along their lengths to have convex radially outer surfaces; andC. the tubular member
 3. radially outwardly projecting ledge means onthe outer end of said extension, spaced from the flange; B. an axiallyslitted spring ring embracing said extension and confined against axialdisplacement by said ledge means, said spring ring having a plurality ofcircumferentially spaced integral fingers that project obliquely towardsaid flange and radially outwardly,
 3. The combination of claim 1,further characterized by: a flat annular gasket confined between saidflange and said marginal edge portion of said wall of the bottom shellmember.
 4. The combination of claim 1, further characterized by: saidcircumferential edge portions on the tubular member being defined by aradially inwardly projecting circumferential flange thereon whichflatwise overlies said marginal edge portion of said wall of the bottomshell member.
 5. In an internal combustion engine having a carburetorwith an air duct and having an air cleaner secured across an inlet endof said duct and comprising complementary top and bottom shell members,a filter element enclosed by said shell members, and a rigid tubularmember which extends between walls of the shell members through thefilter element and which is coaxial with the air duct, means forsecuring the air cleaner to the air duct and for holding the componentsof the air cleaner releasably assembled with one another, the lastmentioned means comprising: A. means on the air duct defining